I have been trying to get a good shot on this chubby little bird for a couple of days now. I'm not sure if he's a mockingbird but I wanna say he is from a shot I got of his behind (which I thought was cute and even thought of using as my photo for today but many might not appreciate). Mr. Robin (photo 395) is not fond of him and I have seen him chase this poor bird around our holly tree. I'm thinking that it's either he is still young that's why he's fluffy or maybe he just likes to make himself look bigger...trying to stay on guard against Mr. Robin. I would appreciate it if somebody could confirm that he is a mockingbird.
This does in fact look like a Mockingbird. As far as him being "puffed up", most birds do this in colder temperatures as a way of keeping warm. Nice shot.